Alternating-current dynamo



2 Sheets-Sheet. 1.

(No Model.)

\ J. J. WOOD. QALTBRNATING CURRENT DYNAMO. No. 489,065.

" Patented Jan. 3, 1893.

FIG. I.

WITNESSES:

(No Model.) 2 Sheets-Sheet 2.

' J. J. WOOD.

ALTERNATING CURRENT DYNAMO.

No. 489,065. 4 PatentedJan.3,1893.-

INVENTOR:

WITNESSES: I v ml I 6;44164 71 M 2 77s.! By lus iomeys,

To all whom it may concem:

, UNITED STATES PATENT O ICE,

JAMESYJ. wooD,'oF FORT waY-nn-innmna.

ALTERNATING-CURRENT DAYNAMVO.

SPECIFICATION forming part of Letters Patent No. 489,065, dated January3, 1898.

Application illed July 22, 1892- Be it known thatl, JAMES J. W001), acitizen of the United States, residing at Fort Wayne,- in the county ofAllen and State of Indiana, have invented certain new and usefullmprovements in Alternating-Current Dynamos, of which the following is aspecification.

This invention relates to dynamo electric machines for generatingalternating currents,

or by the addition of a current rectifying commutator, for generatingpulsatory currentsof uniform direction It relates especially to dynamosof that class wherein the armature is a stationary ring, and

the field-magnet is mounted to revolve with' in this ring, and-hasoutwardly turned polar armsof. successively alternated polaritiesterminating closely adjacent to the inner'fac'e of the armature core.

My present invention provides an improved construction of revolvingfield-magnet for dynames of this class.

Figure 1 of the accompanying drawings is an end elevation of a dynamoconstructed according to my invention partly in section on the line 1-1in Fig. 2; Fig. 2 is a side elevation thereof, the field-magnet andarmature being in diametrical mid-section on the line 2-2 in Fig. 1;Fig. 3-is a vertical transverse section through the armature andfield-magnet on theline 3-3 in Fig. 2.

LetF designate the field-magnet as awhole, A the armature, a a thearmature coils, E E.

the exciting coils of the field-magnet, and O.

; clamped between annular frames 1) I) having feet I) which rest on andare bolted to the standard B. The frames or rings b may be made of castiron, the laminated armature core 0 being embraced between them and astoned by insulated bolts It passed through them from side to side. Thecore is formed Serial No- 440,92 1t (Ho model-l ring 'shaped core, asillustrated in my applicationSerial No. 369,823,filed'0ctober 30, 1890.

The field-magnet F is mounted on the retative shaft D of the dynamo,which shaft turns in bearings formed on brackets B B which are fastenedto thebase B. The fieldv preferably of steel, through which the shaft Dpasses, and from which.-it is preferably magnetically separated bysleeves-dd of gun metal or other non-magnetizable material.

placed caps or disks g g, preferably of steel, which ,are formedrespectively with polar arms N N and-S S branching from them. The armsof the two disks are of equal number branching from one disk being ofnorth polarity, and the arms S S branching from the other disk of southpolarity. When the two disks are applied, the arms of one disk arealternated with those of the other, forming polar ends projectingbetween polar ends of the other disk with like intervening spaces. Thearms branch from, the disk first in outward direction, then backwardlytoward the middle of the core, and then are-gradually core, terminatingin exterior polar faces which being turned off in a lathe constitute segments of a cylinderof such diameter as to fit freely but closely withinthe armature so that the field-magnet may be rotated therein. Thefield-magnet is wound with one or more we citing coils which are appliedaround the exterior of thecore 1 between the opposite disks g g andwithin the polar arms N S. Two coils are shown, a main coil E and aregulatmagnet is constructed with a tubular core f,

Against the opposite ends of this core are,

and are uniformly spaced, the arms N N turned outward and project awayfrom the 5 tened against the continuous inner face of a ing coil E;These coils receive continuous or pulsatory currents of uniformdirection from any suitable source. The field-magnet being in placewithin the armature,-the polar faces of its arms N S revolve closelyadjacent to the armature projections and coils. Each armature coilreceives consequently the inductive action of alternately north andsouth poles in rapid succession, thereby generating alternating currentsin the armature coils in the manner well understood.

Dynamo machines have before been made wherein afield magnet consistingof a core having polar arms branching from its opposite ends andterminating i1 external polar faces of alternately contrary polarities,has revolved within a ring-shaped armature. In such machines, however,the armature and field-magnet have been made of equal width, and thepolar arms of the fieldmagnet have been simply turned back at the endsand extended across the exterior of the exciting coil thereof, insteadof projecting outwardly away therefrom, and presenting merelytheiroutturned polar ends toa narrow armature, as in my improvedconstruction. The constructions heretofore made have involved a seriousloss of efiiciency by reason of the leakage of lines of magnetic forcebetween the polar arms, and from arm to arm through the armature corewithout cutting the armature coils, with the result that the defect isavoided.

efficiency of such machines has been so low as to render themcommercially impracticable in competition with other alternatingmachines. Myinvention provides an improved construction whereby thisserious practical The polar arms instead of being laid backwardly closeagainst the exterior of the exciting coil,are turned outwardly awaytherefrom at or near the middle thereof, and terminate in outwardlyradiating polar ends. 4 The armature core is reduced from the entirewidth of the field-magnetto a width of approximately only one quarterthereof,

and the polar ends or faces of the arms N- S are made of the samerestricted width as the armat nre core. In this manner the lines offorce are confined and concentrated, being forced to pass from the armsNN to the arms S S by entering the armature core, and consequentlypassing through and cutting the armature coils, so that very nearly allof the lines of force are made effective in the generation of electricpotential. The field-magnet is further strengthened by constructing itwith the disksg g, which are turned inwardly or toward the medial planeof the field-magnet, so that these disks are cupped, as best shown inFig. 2, so that they partly inclose the end portions of the excitingcoil or coils. The cupping of the disks is effected by the formation ofwebs w to between the successive arms N N on one disk and S S on theother, these webs being turned inwardly following the direction of thearms, and thereby constituting the cupped portions of the disks, andbeing also formed with their outlines joining the arms by easy curves,as shown in Figs.1 and 3, so as to distribute the lines ofmagnetic-force to the arms. The inductive effect of the coil setsnpli'nes of magnetic force extending longitudinallythrough the coref,andradially through the disks 1g and by the cupping of these disks topartly embrace the ends of the coils, the exterior portion of the coilis made effective to add to the magnetization of the polar arms bysetting up lines of magnetic force in the cupped portions of the disks,which lines are distributed to the respective arms. The fieldmagnet isthus made stronger than it would be without the disks, and without thecup ping of the disks. w

I claim as my invention the followlug dofined novel featuressubstantially as hereinbefore specified, namely:-

1. The combination of a revolving multipolar field magnet with astationary ring armature within which it rotates, said armatureconsistingof an annular core much narrower than the field magnet, andsuccessive coils applied to said core, and said field magnet consistingof an axial core, an exciting coil around said core, and alternated:polar arms radiating from the opposite ends of said core, bending backaround said coil toward the middle of the core, and having their endportions turned outwardly and terminating in poles facing and closelyadjacent to said armature.

2. The combination with an exterior stationary ring armature havingsuccessive coils applied to the inner side of its core, of a re: volvingfield magnet consisting of an axial core of greater length than thewidth of the armature, an exciting coil around said core, and polar armsradiating from the opposite ends of said core, extended inwardly pastthe ends of the coil toward the middle thereof, each arm enteringbetween two of those of 0pposite polarity, and the polar ends of thearms turned outwardly away from the exciting coil and terminating inpolar faces within and closely adjacent to the armature, whereby thepolar ends approach the armature abruptly on its inner side, and theloss by leakage of IIO lines of force between the polar arms andarmature core without cutting the armature coils is reduced to theminimum.

3. A field magnet consisting of an axial core, an exciting coil aroundsaid core, laterally-expanded heads or disks at the opposite ends ofsaid core, cupped toward the middle thereof so as to partially inclosethe ends of I site ends of said core, bending back around said coiltoward the middle of the oore, each arm entering between two of those ofopposite polarity, and having their end portions turned outwardly toform radiating poles, and webs w w formed integrally with said armsbetween them at the ends of the coil, partly inclosing the endportionsthereof, and joining the arms with curves sweeping toward the rearms, so that the lines of force induced in said .webs are divided anddiverted into the arms.

In witness whereof I have hereunto signed my name in the presence of twosubscribing CHAS. J ONES.

